TemperatureAtaltitudes up to 2438m (8000ft)-Operating: 5°C to 35°C (41°F to 95°F)-Non-operating:5°C to 43°C(41°F to 109°F)At altitudes above 2438m(8000ft)-Maximum temperature when operating under the unpressurized condition: 31.3°C (88°F)

Liquid crystals really are liquid, and they really will freeze. I had an early PDA back in the 90s that I left in the outside pocket of a jacket in Calgary in January. The center of the LCD froze in a big black blotch.

I don't know if the batteries used in laptops can be damaged by low temperatures, but the efficiency of batteries drops with temperature, so you'll get less run time out of a cold battery.

It's probably safe to stay within the defined operating temperatures, but I have operated equipment out of spec before and it works fine. For example, my Canon A95 camera sees heavy use in cold conditions, so cold that moisture freezes on the LCD monitor. The camera still works fine, but it gets horrible battery life (once the batteries defrost, they work without recharging).

Basically, keeping it in the car once or twice in a pinch probably won't hurt, but I wouldn't do it too often.